Britain has flatly denied having any advance knowledge of Israeli plans to assassinate a senior official of the Palestinian group Hamas in Dubai last month.

Whitehall sources today dismissed as "nonsense" a report claiming that Israel's secret service, Mossad, had informed the UK of possible complications arising from the use of British passports in an unspecified "overseas operation".

Today's Daily Mail reports that "a member of Mossad … said the Foreign Office was also told hours before a Hamas terrorist chief was assassinated in Dubai. The tip-off did not say who the target would be or even where the hit squad would be in action."

The paper quotes an unnamed "British security source" as saying: "This is a serving member of Israeli intelligence. He says the British government was told very, very briefly before the operation what was going to happen. There was no British involvement and they didn't know the name of the target. But they were told these people were travelling on UK passports."

But a Foreign Office spokesman said today: "Any suggestion that the government knew anything about the murder before it happened is completely untrue, including the use of UK passports."

The Foreign Office has said it received details of the British passports last Monday "a few hours before the press conference [by police in Dubai]. We were able to respond to the Dubai authorities on the authenticity of the passports the next day."

Lieutenant General Dahi Khalfan Tamim, the head of Dubai police, admitted that the relevant embassies had not been contacted until shortly before the identities of the suspects were revealed. "We wanted to complete the investigations and be sure of everything before we contacted the embassies," he said.

The Hamas official Mahmoud al-Mabhouh, killed on January 19, is said by Israel to have been responsible for the killing of two Israeli soldiers as well as being in charge of the Islamist organisation's clandestine relationship with Iran.